title: A modified in vivo flow variation technique of microdialysis for sampling uremic toxins in the subcutaneous interstitial compartment.
abstract: BACKGROUND
  Uremic toxins are typically measured in plasma and little is known of their interstitial concentrations. We undertook experiments to validate a microdialysis technique for simultaneous recovery of small and large uremic toxins in the subcutaneous interstitial fluid (ISF).
  
  
  METHODS
  Microdialysis catheters were inserted into the subcutaneous interstitium of 8 subjects (controls and uremic patients) and perfused using two different solutions at incremental flow rates to determine analyte recovery and ISF concentrations of urea and protein.
  
  
  RESULTS
  10% dextran-40 perfusate allowed the determination of interstitial concentrations of urea and protein reliably, by virtue of the exponential decay of their concentrations in the microdialysate with incremental flow rates (R(2) = 0.63-0.99). Interstitial and plasma urea correlated well (r = 0.95), as did interstitial urea from distant anatomical sites (r = 0.96).
  
  
  CONCLUSIONS
  Cutaneous microdialysis with dextran-40 allows measurement of small and large molecule concentrations in ISF, creating an opportunity to characterize ISF in uremia.
authors.affiliation: Manchester Institute of Nephrology and Transplantation (MINT), Central Manchester University Hospitals Trust, Manchester, UK. Leonard.ebah @ cmft.nhs.uk
authors.forename: Leonard
authors.initials: L
authors.lastname: Ebah
authors.forename: Paul
authors.initials: P
authors.lastname: Brenchley
authors.forename: Beatrice
authors.initials: B
authors.lastname: Coupes
authors.forename: Sandip
authors.initials: S
authors.lastname: Mitra
mesh_terms: D000328:Adult; D000368:Aged; D057785:Catheters; D003911:Dextrans / Q000737:chemistry; D015314:Dialysis Solutions; D045604:Extracellular Fluid / Q000737:chemistry* / Q000378:metabolism; D005110:Extracellular Space / Q000737:chemistry* / Q000378:metabolism; D005260:Female; D006801:Humans; D007260:Infusion Pumps; D008297:Male; D017551:Microdialysis / Q000295:instrumentation / Q000379:methods; D008875:Middle Aged; D010952:Plasma Substitutes / Q000737:chemistry; D011506:Proteins / Q000032:analysis*; D051436:Renal Insufficiency, Chronic / Q000378:metabolism* / Q000503:physiopathology; D040521:Subcutaneous Tissue / Q000737:chemistry* / Q000378:metabolism; D014508:Urea / Q000032:analysis*; D014511:Uremia / Q000378:metabolism* / Q000503:physiopathology
chemical_list: D003911:Dextrans; D015314:Dialysis Solutions; D010952:Plasma Substitutes; D011506:Proteins; D014508:Urea